Cats are now many people's favorite pets. Although the cat looks lovely, the cat's excreta always stinks. When the cat defecates and urinates in an improper place, such as a sofa or a carpet, it will become difficult to dispose of excreta. There is a device for allowing cat's defecation and urination (litter box), and cat litter for burying excreta is filled therein, besides, the litter box used by the cat will be mixed with excreta including urine and feces. It is necessary to clean the litter box frequently, for preventing affecting the environmental hygiene. In addition, since the cat litter's consumption is great, it will considerably cost a lot in a prolonged period.